Filter apparatus using filter mediums are shown in my issued patents U.S. Pat. No. 5,059,318 issued Oct. 22, 1991 for Fluid Seal For A Travelling Sheet Filter Press and U.S. Pat. No. 5,292,434 issued Mar. 8, 1994 for Filter Apparatus And Method Using Belt Filter Medium. In such filters separable plate members are pressed together to form a filter chamber. The plates have mating surfaces and hollow interior portions that create a filter chamber. A filter medium is placed between the mating surfaces before the plates are closed. In the usual operation, a slurry of liquid and solids is introduced into the formed chamber above the filter medium and, in a series of operations that may include forcing wash fluids, liquids or gasses through the slurry within the chamber, fluids are forced out of the slurry and through the filter medium to produce a dry filter cake of solids on the filter medium within the chamber. The plates may then be separated leaving the filter cake on the filter medium and the filter medium may be advanced out of the filter chamber to be replaced by a clean filter medium for a repeat operation of the filter mechanism. The filter medium may be advanced to a dump position for the filter cake and then cleaned and reused or may be discarded.
Because slurries are of varied formation and characteristics the filter medium used in the filter apparatus shown in my issued patents and in functionally similar filter apparatus frequently are specifically designed for the slurry being encountered. Some slurries include coarse solids and some include almost colloidal suspensions of fine solids. Filter media for filter apparatus operating with these variations in particle size need to be designed to provide the desired permeability for the media while providing a media with openings that will capture the smallest particles that are desired to be retained. The filter media must also be capable of performing the desired filter operation without becoming clogged by retained solids.
In designing a filter media that is intended for repeated uses, it is desirable to produce a filter media that will release the produced filter cake and may be easily cleaned for reuse in the filter chamber.
Slurries are also of varying chemical characteristics; some being toxic, some caustic, some acidic, some hot, some cold. Filter media designed for these different chemical characteristics may be woven with fibers that can withstand the conditions to be encountered within the filter chamber.